The invention relates to a water outlet for a low pressure sanitary outlet fitting.
There already exist hot water tanks that are mounted under a wash basin within the framework of a decentralized hot water supply. Hot water tanks of this type are configured as unpressurized tanks that can be heated. Moreover, their volume can contract or expand as a function of the water temperature. The volume of the water located in the tank changes, as a result of which the water volume expands in the event that the water is heated.
The jet regulators, which are generally provided on the outlet end of a sanitary outlet fitting, have comparatively small holes, which are located, for example in the area of their jet divider and can be clogged by the dirt particles in the water. As a result, there is the risk that the outlet fitting can be closed so tightly that a dangerous pressure can build up in the water tank. Therefore, low pressure fittings do not usually use a standard jet regulator. Rather these low pressure fittings use jet regulators that have significantly larger flow cross sections. However, it is a particular drawback that in the event of temperature induced expansions and contractions in the water tank, the water column in the fitting can also change. Especially in the course of closing the outlet fitting, the water column, which is still standing in the fitting, will typically flow out of the fitting and continue to drip or flow, because the requisite free cross sectional area has to be dimensioned. This factor is usually perceived to be annoying.
An additional drawback with the commercially available low pressure jet regulators is that they often react in a sensitive way to an inflow sided flow that deviates from the axial symmetry, as is often the case with hand-held shower heads and cast iron fittings. The result is a poor and splashing non-homogeneous jet pattern.
German patent document DE 10 2004 044 158 B3 discloses a prior art water outlet mouthpiece having a switchable jet regulator insert, which has a cleaning jet channel and at least one flow chamber having a large number of water egress nozzles. At least one inflow aperture of the flow chamber is controllable by means of at least one valve, which is biased into its closed position, such that it can be opened by the water flowing in, by a predeterminable banking-up pressure of the water. For automatic switching between a sharply bundled cleaning jet (as is necessary, for example, for cleaning a razor) and a standard enlarged and especially aerated soft jet, a valve of the jet regulator insert that is provided in the water outlet mouthpiece known from the prior art has a valve piston that is axially displaceable in the direction of flow of the water and a valve disk, and has at least one water inlet aperture, which leads to the cleaning jet channel that extends through the hollow valve piston.
The cleaning effect, targeted in German patent document DE 10 2004 044 158 B3, assumes that the outlet fitting, known from the prior art, is a high pressure outlet fitting. Moreover, the jet regulator insert provided in German patent document DE 10 2004 044 158 B3 does not have a bypass channel, which bypasses the perforated structure. And finally, the cleaning jet channel, which is provided in the jet regulator insert, known from the prior art, and which runs through the valve piston, is always open and precisely not switchable between on open and a closed position.
German patent document DE 38 17 270 A1 discloses a prior art jet regulator having a jet regulator housing, in whose passage channel is inserted a jet regulator insert. In order to reduce a backflow pressure, which builds up more and more as a result of dirt on the rear side of the insert, the passage cross section of the jet regulator can be enlarged upon exceeding a predeterminable backflow pressure, in that the jet regulator insert is released from its normal operating position and either falls out of the jet regulator housing or else passes into a triggering position, in which, for example, a ring channel, which enlarges the overall passage cross section, is formed around the insert.
The jet regulator insert, which is provided in the prior art jet regulator, known from German patent document DE 38 17 270 A1, is positioned in a standard operating position inside the passage cross section in such a way that the entire stream of liquid flows through the jet regulator insert, whereas, in contrast, the jet regulator insert is released in response to the triggering device and can then fall out in the outflow direction, in order to then totally release the passage channel until the jet regulator is exchanged or serviced.
U.S. Pat. No. 4,313,564 A discloses a prior art jet regulator, which has in the area of its jet divider a bypass channel with a bypass valve, which moves into its closed position as a consequence of a pressure increase on the inflow side. In contrast, when the water pressure is low, this bypass valve stays in its open position, so that dirt particles can be flushed out through the bypass channel. The bypass valve of the jet regulator, known from the prior art, is open in the unpressurized state or at low water pressure conditions and causes the perforated structure, which is provided in its area, to be not capable of holding precisely water in the unpressurized state.
Therefore, one object of the invention is to provide a water outlet of the type described, that is designed as an idle safety and is highly reliable.
This and other objects and advantages are achieved by the water outlet in accordance with the invention, which has a perforated structure that is permeable to air in a direction counter to the water outlet direction, and that, in the unpressurized state, holds water as a consequence of the surface tension. The flow holes of the perforated structure have a small flow cross section, in order to produce a surface tension that is adequate to hold the water column that remains in the outlet fitting, after the outlet valve of the outlet fitting has been closed, and to counteract an afterflow and idling of this water column. If the water tank increasingly contracts as the heated water cools down, then it is still possible to suck in air through the perforated structure and to equalize the pressure. If there is the risk that, as the temperature of the water supply increases, excessive pressure will build up (because, for example, the perforated structure is soiled by the dirt particles entrained in the water), a bypass having at least one bypass valve becomes operative. As a consequence of the associated pressure increase, the bypass valve is moved from its closed position into its open position counter to a resetting force and can bring about a decrease in pressure.
The water outlet in accordance with the invention can be permanently installed in a sanitary outlet fitting. In order, however, to be able to install the inventive water outlet simply and advantageously into a wide range of outlet fittings, it is practical to design the water outlet as an insert cartridge, which can be inserted into the outlet end of a sanitary outlet fitting.
In order to offer as little flow resistance as possible to the water jet that flows through, and to achieve the largest possible passage cross section in the areas of the perforated structure without losing adequate surface tension there, it is advantageous to design the perforated structure as a preferably honeycomb-like screen surface.
In one preferred embodiment of the invention the bypass is disposed centrally in the perforated structure so that the latter, (which may also be designed, if required, as a screen surface) surrounds the central bypass in a ring shape.
It is especially advantageous if the bypass valve has a closing element that is guided moveably along the narrow edges of flow guide walls, preferably surrounding and extending radially outward from in a radiating manner the closing element. The flow guide walls, which are disposed radially not only form a reliable sliding guide around the closing element of the bypass valve, but can also readily shape the water emerging from the water outlet to form a homogenous, non-splashing composite jet.
In order to avoid the generation of any undesired turbulence and any unnecessary flow resistance in the water by the closing element (around which flows the water that is flowing through), it is advantageous to design the closing element in the shape of a ball, spherical segment or mushroom and with a subarea that tapers off in the direction of flow.
Working on this basis, in a preferred embodiment of the invention, the closing element is designed at least in certain areas as a segment of a sphere (hereinafter referred to as a “spherical segment”), so that, when the bypass valve is in the closed position, a base proportional of the spherical segment closes the valve port of the bypass valve. In this embodiment, the closing element with its spherical segment extends as far as up to the individual jets produced by the flow holes of the perforated structure. This embodiment is characterized by a low resistance and homogeneous jet guide and formation.
In order not to set the closing element, guided in the water outlet, into an undesired and noise-generating oscillation, and in order to be able to guide the closing element in an easily moveable manner and yet with minimum play in the water outlet, it is advantageous if the closing element includes a guide pin, which is disposed preferably on the outflow side, and is guided displaceably in a guide sleeve that is held stationarily in the water outlet. At the same time the guide pin and the guide sleeve are guided along narrow contact lines with comparatively low friction, if the guide sleeve has a polygonal and preferably hexagonal inside guide cross section, in which the guide pin having a round outer cross section is displaceably guided.
In order to be able to move the closing element with as little trouble as possible against a constant reset force, it is advantageous if the closing element is moveable against the reset force of at least one return spring.
The formation of a homogeneous composite jet in the water outlet in accordance with the invention is assisted if the flow holes are enclosed by flow guide walls. So that these flow guide walls can easily fulfill their jet guiding function in an especially effective way, it is advantageous if the flow holes have a flow length that is smaller than their inside flow cross section or, if need be, the same size. This feature offers advantages with respect to a better jet pattern especially if the incoming flow is at an angle.
So that the water outlet in accordance with the invention can safely lower an undesirably high pressure, and so that this safety function is not negatively affected by operating errors (for example, by closing the water outlet with the palm of the hand, the finger tips or a plane surface), it is advantageous if the outflow side peripheral rim area of the cartridge housing is designed in an approximately crown shaped or crenellated manner, by outward formations and inward formations.
Additional features of the invention are apparent from the following description of the embodiments of the invention in conjunction with the claims and the drawings. The individual features may be realized in each case by themselves or in any combination in the case of an embodiment according to the invention.